2009-01-22

Spirit Sol 19

As I'm coming in, Jeng Yen tells me it's going to be a slow day. Bad weather over Australia interfered with our comm link, so the day's sequences didn't get uplinked. They tried to save the sol by uplinking later through Madrid, but ran into some other problem when they did so. No RAT today.

In a way, that's a good thing. The MI team has been carefully examining their recent images, and they appear to have come from a spot nearer to Blue than to Prospect. This could indicate a potentially serious IDD positioning error, so Frank is checking out the playback and imaging. But he's already skeptical, because so far everything looks right. It's still possible that the rover settled overnight, sinking slightly into the soil while the IMU was off. Which is unlikely, and would suck, but it is possible.

A developer for some other software on the project is trying to push me into debugging their problem. I wouldn't fall for it, except that I went to hear Andy Mishkin talk about his book last night, and one of his answers to an audience question was about the importance of having people on your team who will step up to the plate and solve problems that aren't strictly in their own domain .... Bah, stupid conscience. So I solve the damn problem for them -- it turns out they hadn't delivered the file they thought they'd delivered, they'd delivered an older version or something. Grr.

Fixing that problem makes me late to the downlink assessment meeting once more. But not very late, at least. As I arrive, Eric is telling them that as far as we can tell, we really did put the MI on Prospect, not Blue. It's possible there's been some camera drift since the cameras were calibrated, but that wouldn't be enough to account for the claimed error. He asks for help in assessing whether there was an error and where it was if so.

In response, the scientists seem to be backpedaling a little. But there is doubt. It's a hard problem, taking a micro-view of an area and fitting it precisely into a macro-view of the same area. Someone likens it to the localization problem -- figuring out exactly where we landed. It's an apt comparison, and since that problem took a few days to solve, so might this one. They form a "tiger team" (I hate that phrase, but I love tigers, so it balances out) to solve it.

I am interrupted by a phone call from the Milwaukee TV guy whose interview I missed yesterday. We do our little five-minute thing on the air. I think I'm getting better at this, making only one real mistake: early in the interview, he asks for some numbers, and I give them to him. Understand that this really is an error: instead of telling him that the rover traverses 1cm per second on average, I should tell him how long it takes for the rover to cover a football field or something. Even when you're only a phone voice on the TV, you need to think in terms of pictures.

A good answer would have been something like this: "When you take a step, that's about three feet. The rover takes maybe 30 to 90 seconds to cover that same distance. But then, the rover weighs four hundred pounds and uses only about as much power as two light bulbs, so you can't expect it to go too fast even in Mars's lower gravity." Bam, that's an answer. It has the numbers, but it's packed with imagery.

Anyway, other than that, I think I did OK. One strange thing I've noticed about phone interviews is that they actually hang up when it's over. I kind of expected that they'd stop taping or whatever and then talk to you a little more, but no, it's wham, bam, thank you, ma'am. (Actually, the Raleigh guys did talk to me for a few moments after we stopped taping. Maybe that's Southern politeness.)

Back in the meeting, Phil Christensen (MTES) is talking about interferograms. The MTES, he says, measures the delta radiance between itself and the outside world. The best operating time they've found so far is about 1PM, because then the MTES is warm (it's inside the WEB) and the surface is cooling. But that analysis was done on the lander; they may need to reanalyze the situation on the surface. They also have this problem where they sometimes get the sign of the delta wrong, so that things that are in fact very warm look very cold. They can fix this by changing the flight software, but it might take a while to validate everything and convince the FSW people to patch the rovers.

Art comes in and says we got no Odyssey telemetry, so there will be no science tomorrow. Sol 19 will definitely be a recovery sol. Art is a smart guy and leaves before they can lynch him.

In another blow to science, they're paring back on the stand-down sols [during the Opportunity landing], which are coming up soon. The sequences for those sols originally optimistically assumed a 400Mbits/sol downlink, but we've been averaging more like 180Mbits/sol. So they've cut a lot of stuff out.

One happy consequence of a recovery sol is: no SOWG today. They have an informal version of it, but it's almost nothing like the real thing. The chair reports a lot of concern about the spacecraft, since the AM comm was erratic and we've heard nothing from the spacecraft since then. But Andy thinks the rover just overheated, in which case it will naturally be OK as it cools, and we're fine. I'm not worrying about it.

Coming up: RAT on sol 20, spectroscopy of the resulting hole on sol 21. This will continue through the stand-down. There's some discussion of whether we should analyze the soil instead of Adirondack during the stand-down, but the sentiment (and resulting vote) is overwhelmingly for the rock. We've done soil already, and "soil is everywhere," as someone points out. Rock beats soil.

Arvidson ends the meeting, saying, "Why don't we just end school early -- it's a snow day." There's a mixed feeling of tension and relief as the room empties.

2 comments:

Jason Perry said...

Great reading so far!

Love the foreshadowing...

Tim said...

And so it begins!!